Production of artificial materials



Patented Feb. 21, 1939 PATENT OFFICE PRODUCTION OF ARTIFICIAL MATERIALS William Alexander Dickie and Percy Frederick Combo Sowter, Spondon, near Derby, England, assignors to Celanese Corporation of America, a corporation of Delaware No Drawing. Application October 26, 1929, Se-' rial No. 402,785. In Great Britain November This invention relates to the production of artificial filaments, threads, ribbons, films and other products by wet spinning processes, particularly from solutions of cellulose derivatives, foxexample cellulose acetate, formate, propionate, butyrate or other -:.arboxylic acid or other esters of cellulose, or methyl, ethyl or benzyl cellulose or other cellulose ethers.

According to the present invention filaments, threads, ribbons, films and other products are wet spun, particularly from solutions of cellulose derivatives, under such conditions that the products emerge from the coagulating bath in a plastic condition, that is to say in a conditionin which they do not exhibit elasticity.

In U. S. Patents Nos. 1,465,994 and 1,467,493, We have described processes for the manufacture of filaments, threads or films by extruding solutions of cellulose acetate into aqueous baths containing solvents or latent solvents for the cellulose acetate. The said patents specifically describe only the use of relatively dilute solutions of solvents.

We have now found that much superior products may be-obtained by having present during the coagulation solvents or strong swelling agents in relatively high concentration. Preferably the concentration is such that the cellulose acetate or other ester or ether is not fully coagulated on emergence from the coagulating bath and. the

' products at the point of emergence may be so plastic that if brought together they will coalesce. By this means we have found that greatly improved products may be obtained and. moreover during the coagulation it is possible to apply a stretch so as to produce products of great fineness. For example in the case of filaments it-is possible to apply a stretch to produce deniers of 1.0 to 0.75 or even, less. The requiste concentration of solvent or strong swelling agent in the coagulating bath may either be achieved by starting with a coagulating bath containing the'solvent or strong swelling agent in the desired concentration or by incorporating the solvent or strong swelling agent in the spinning solution itself and eifecting the coagulation so that the required concentration is attained or so that coagulation is not complete and plastic products emerge from the coagulating bath. For the sake of brevity strong swelling-agents are hereinafter included inthe term solvents.

Preferably the solvents employed are such that by reason of their innocuous properties they need not be entirelywashed out of the filaments or other products and a. residue of solvent can re- 13 Claims. (Cl. 18-54) main therein to be removed by evaporation only. Moreover, the best results have been obtained with organic solvents which are less volatile than the non-solvent liquid or diluent used in the coagulating bath. In the case of employing water or alcohol as the non-solvent liquid for the precipitating bath, we have found that diacetone alcohol, diethyl tartrate, monoand diacetin and ethyl lactate are particularly suitable.

Mixtures of two or more solvents of low volatility may be employed and further it is sometimes advantageous to employ mixtures of one or more solvents of low volatility with one or more solvents of high volatility. For example in using a bath containing aqueous diacetone alcohol an addition of acetone to the bath appears to give still further increased strength in the filaments, films or other products obtained.

Before collecting the products, for instance on bobbins, in the form of cheeses etc., excess of solvent should be removed, since otherwise coalescence is liable to occur. Such coalescence is prevented prior to the collecting operation by reason of the bulk of liquor adhering to the products. The excess solvent may be removed, for example, by washing with water or other non-solvent media, with salt solutions or with solutions of solvents of lower concentration than those adhering to the products. Washing may, if desired, be efiected with solutions of salts, or solvents of continually or continuously decreasing concentration. The washing may be eflected, for example, by spraying or in a centrifugal spinning box.

The concentration of solvent in the coagulating .bath required to produce the desired effects will vary somewhat with the conditions'of spinning or extrusion. With acetone solutions ofi cellulose acetate we have found that highly satisfactory results may in general be obtained with 25-65% solutions of diacetone alcohol, diethyl tartrate or ethyl lactate. Variations may be made according to the cross-section of the filaments etc., being spun. For example, .with aqueous solutions of diacetone alcohol as coagulating baths for acetone 2 particular non-solvent medium in the coagulating bath. Water is preferred, but any other suitable medium may be employed. For example with cellulose acetate or other cellulose esters one may employ methyl or ethyl alcohol or homologues thereof or hydrocarbons, for instance benzene, toluene and their homologues or other coal tar hydrocarbons, and gasoline, kerosene or other petroleum hydrocarbons. The solvent used should of course be soluble in the non-solvent medium of the coagulating bath.

During the coagulation a stretch may be imparted to the filaments or threads so that fine filament deniers may be produced from relatively large jet orifices.

As indicated above, instead of employing in the coagulating bath solvents for the cellulose deriviative, such solvents may be incorporated in the spinning or extrusion solutions themselves in sufficient quantity to exert the required solvent action in the coagulating bath. The quantity required will vary with the solvent chosen and with its miscibility or solubility in the non-solvent medium employed in the coagulating bath.

Such solvents may be present as the sole solvents for the cellulose derivatives or other solvents, for example more volatile solvents such as acetone, may be present in addition.

The two methods given above of subjecting the filaments, films or other products to the action of solvents during coagulation may furthermore be combined. Thus for example a spinning solution containing a solvent of lower volatility than the non-solvent medium in the coagulating bath 'may be spun into a coagulating bath containing the same or a different solvent. In'such cases of usin a solvent both in the spinning solution itself and in the cogulating bath, the quantity of solvent in each need not by itself be sufiicient to produce the eifect, the criterion being that during the coagulation the filaments, films or other products should be in contact with a solvent medium of sufficient concentration to exert the required action. By suitably adjusting the proportions of solvent present during the coagulation, filaments, threads, ribbons or other products of almost any desired degree of lustre may be produced, for example products having practically no lustre, products having a lustre similar to that of natural silk or products having a relatively high lustre. In general the higher the concentration ofthe solvent present during coagulation the higher will be the lustre of the products.

The present invention further enables very strong filaments, threads, ribbons, films or other products to be produced from acetylation or esterification solutions. Thus for example an acetyla-. tion solution containing cellulose acetate dissolved in acetic acid may be spun into a 1 to 30%, and especially a 5 to 25%, aqueous solution of acetic acid, or such a coagulating bath may contain in addition another non-solvent medium for instance methyl or ethyl alcohol; Primary acetylation or esterification solutions, which do not contain a catalyst or other agent liable to aifect deleteriously the filaments, films or other products, are

of particular value in this connection and as examples of such solutions may be mentioned the products of the acetylation or esterification processes described in U. 8. applications Nos. 301,928 dated August 24, 1928, 301,929 dated August 24, 1928, 301,92! dated August 24, 1928, 321,750 dated November 24, 1928, and 321,751 dated November 24, 1928. For example, an acetic acid solution containing 913% of cellulose acetate produced by using as catalyst in the acetylation a mixture of ferric chloride and hydrochloric acid as described in U. S. application No. 301,927 dated August 24, 1928, yields very strong lustrous filaments on spinning into an aqueous solution of acetic acid of about 20% concentration. The esterification solutions used may be solutions of the primary acetates or esters or of secondary acetates or esters produced by subjecting the primary products in their primary esterification solutions to secondary treatments as describedfor example in the applications referred to.

It is preferable to destroy any remaining acetic anhydride or other esterifying agent before spinning or extruding the esterification solutions, but if desired, acetic or other anhydride may remain in the solutions and in such a case it is advantageous to use in the coagulating bath a reagent, for instance methyl or ethyl alcohol, which will react with the anhydride to produce a substance which is itself capable of exerting or of assisting to exert the solvent action on the filaments, films or other products.

In any of the processes of the present invention non-solvent media may be added to the solutions of cellulose derivatives before spinning or extrusion, the quantity of non-solvent media being varied from nil to an amount which just fails to precipitate the cellulose derivative. Furthermore, the coagulating bath may, if desired, include a lubricant, for instance an oil, so as to lubricate the threads or filaments for subsequent textile operations. The lubricant may, for example, be present in the form of an emulsion or as an oil or other layer on the bath.

Non-lustrous products or products of relatively low lustre produced according to the present invention are peculiar in that their lustre is not increased by ironing or by known methods of treatment with solvents. On the other hand lustre may be reduced or removed from the products of the invention by treatment with moist steam or other hot or boiling aqueous media.

The finished filaments, threads, ribbons, films or other products, produced according to the present invention may, if desired, be subjected, under tension or not, to an additional treatment with solvents so as still further to improve their properties.

The following examples illustrate the invention but are not to be considered as limiting it in any way I- Example 1 A 25% solution of cellulose acetate in acetone is extruded through suitable spinning nozzles into a coagulating bath containing parts by volume- Example 2 A 25% solution of cellulose acetate in acetone is extruded through suitable spinning nozzles into a coagulating bath containing 50 parts of diacetone alcohol to 50 parts of rectified spirit. The filaments are drawn out and further treated as in Example 1.

Example 3 A 25% solution of cellulose acetate in acetone is extruded as in the above examples, but using a coagulating bath containing 45 parts of ethyl lactate to 55 parts of water, the filaments being drawn out and further treated as before.

Example 4 A 25% solution of cellulose acetate in a solvent mixture consisting of 25 parts of diacetone alcohol-to 75 parts of acetone is spun into filaments as described in Example 1, but using as coagulating bath a 40% solution of diacetone alcohol in .water. i

Example 5 described above, instead of subjecting the filaments, threads, ribbons, films or other products to the action of relatively concentrated solutions of solvents or strong swelling agents during co-' agulation, such solutions of solvents or strong swelling agents may be applied to the products after coagulation, for example in a secondary I bath immediately following the coagulation bath.

Such secondary baths may be identical" in composition with the coagulating baths described above in relation to the main process of the present invention. The secondary baths may bring the filaments, threads, ribbons, films or.

other products to a state of plasticity similar to that of the products of the main process on The plasticity maybe such that the products on emergence from the secondary baths will coalesce if brought together. In the case of using such secondary baths, coagulating baths of any suitable composition may be employed. Preferably they will contain the same non-solvent medium as that employed in the secondary bath or a non-solvent medium readily miscible therewith. They may further contain solvents for the cellulose derivatives, as set forth for example in U. S. Patent No. 1,465,994 and No. 1,467,493, but particularly or- I ganic solvents. For example a very advantageous procedure isto employ as coagulating bath an aqueous solution of diacetone alcohol and to pass the filaments or other products into a secondary bath containing an aqueous solution of diacetone alcohol of relatively high concentration.

A stretch may be applied to the products during their passage through the secondary baths, whether or not a stretch is applied during coagulation. Fine denier filaments may thus be produced.

The treatment of the products after emergence from the secondary baths may be similar to that applied to the products of the main process after their emergence from; the coagulating baths. Lubricants may be applied in secondary baths as described above with reference to coagulating baths.

The following example illustrates the above modification of the main process:-

Eanmple 6 A 25% solution of cellulose acetate in acetone Patent is:-- a

r plastic condition, and subsequently removing the ments, threads, ribbons, films and like products,

3 tone alcohol to '75 parts of water and the thread i is carried directly through a secondary'bath consisting of 55 parts of diacetone alcohol to 45- parts of water. 7 The stretch necessary to produce the required filament denier is applied to the 5 ghiead during its passage through the secondary The phrase "continuously with its shaping, with a liquid bat where employed in the following claims is to be understood, where the context admits, to include both treatments effected in the coagulating bath and also treatments effected in subsequent baths before the materials are colletced and dried. The term after-treatment bat where employed in the following claims denotes a treatment bath to which the materials pass after leaving the coagulating bath and before they are collected and dried.

What we claim and desire to secure by- Letters 1. Process for the manufacture of artifical filaments, threads, ribbons, films and like products,

. which comprises imparting the required shape to,

a composition containing'anorganic derivative of cellulose dissolved in a neutral solvent medium, continuously with the shaping operation passing" the shaped composition into a liquid bath, which bath comprises a non-solvent for the organic derivative of cellulose and between and 65% of a less volatile neutral solvent therefor selected from the group consisting of diacetone alcohol, ethyl lactate and diethyl tartrate, said non-solvent being miscible with said neutral solvents, and which bath maintains the "composition in a product from the bath and removing solvent from the product.

2. Process for the manufacture of artificial filaments, threads, ribbons, films and like products, which comprises imparting the required shape to a solution-of an organic derivative of cellulose in a neutral solvent medium, continuouslywith the shaping operation passing the' shaped composition into a liquid bath, which bath comprises a non-solvent for the organic derivative of cellulose and between 25 and 65% of a less volatile neutral solvent therefor and which maintains the compositionin a plastic condition, said non-solvent and less volatile neutral solvent being miscible, stretching the composition during its passage through the bath and subsequently removing the product from the bath, washing the product to remove solvent therefrom and drying and collecting the product.

3. Process for the manufacture of artificial filaments, threads, ribbons, films and like products, which comprises imparting the required shape to a solution of an organic derivative of cellulose in a'neutral solvent medium, continuously with the shaping operation passing the shaped composition into an aqueous bath, which bath contains about of a neutral solvent for the organic derivative of cellulose which isless volatile than water and which maintains the composition in a plastic condition, stretching the composition during its passage through the bath and subsequently removing the product from the bath,

removing solvent-therefrom and drying and collecting the shaped products.

4. Process for the manufacture of artificial filawhich comprises imparting the required shape to a composition containing an organic derivative of cellulose dissolved in a neutral solvent medium,

passing it directly into a liquid coagulating bath, 7

moving the product from the bath and removin solvent therefrom.

- 5. Process for the manufacture of artificial filaments, threads, ribbons, films and like products, which comprises extruding a solution ofan organic derivative of cellulose in a neutral solvent medium through a suitable shaping device into a liquid coagulating bath, which bath comprises a non-solvent for the organic derivative of cellulose and about 40% of a less volatile neutral solvent solvent therefor and in which the shaped solution is brought toand maintained in a plastic condition, said non-solvent and less volatile neutral solvent being miscible, and subsequently removing the product from the bath, removing solvent therefrom and drying and collecting the product.

6. Process for the manufacture of artificial fila- .ments, threads, ribbons, films and like products,

which comprises extruding a solution of an organic derivative of cellulose in a neutral solvent medium through a suitable shaping device into 'an aqueous coagulating bath, which .bath comprises wat'er and'between 25 and 65% of a less volatile neutral solvent for the organic derivative of cellulose and in which the shaped solution is brought to and maintained in a plastic condition, stretching the plastic product during its passage through the bath and subsequently removing the product from the bath, washing the product to remove solvent therefrom and drying and collect: ing the product.

7. Process for the manufacture of artificial filaments, threads, ribbons, films and like products. which comprises imparting the required shapeto a compomtion containing an organic ester of cellulose dissolved in a neutral solvent medium,

it directly into a liquid coagulating bath which maintains the composition in a plastic condition, said bath comprising a liquid aliphatic alcohol, which is a non-solvent for the organic ester of cellulose, and between 25 and 65% of a less volatile neutral solvent therefor selected from the group consisting of diacetone alcohol, ethyl lactate and diethyl tartrate, dissolved in the aliphatic alcohol, and subsequently removing the product from the bath and removing solvent therefrom.

8. Process for the manufacture of artificial filaments, threads, ribbons and like products, which comprises extruding a solution of an organic derivative of cellulose in a neutral solvent medium through a suitable shaping device into an aqueous coagulating bath which contains about 40% of a neutral solvent for the orga'niederlvative of cellulose which is less volatile than water and in which the shaped solution is brought to and maintained in a plastic condition, stretchin the plastic product during its passage through the bath and subsequently removing the product from the bath, removingsolvent therefrom and {drying and collecting the product. i 9.. Process for the manufacture of artificial filaments, threads, ribbons and like products, which comprises extruding a solution of cellulose acetate in a neutral solvent medium through a suitable shaping device into an aqueous coagulating bath which containsv about 40% of a neutral solvent for the cellulose acetate which is less volatile than water and in which the shaped solution is brought to and maintained in a plastic condition, stretching the plastic product during its passage through the bath and subsequently removing the product from the bath, removing solvent therefrom and dryingand collecting the product.

10. Process for the manufacture of artificial filaments, threads, ribbons and like products,

which'comprlses extruding a solution of cellulose acetate in a neutral solvent medium through a suitable shaping device into an aqueous coagulating bath containing diacetone alcohol in a concentration of about 40% wherein it is brought to and maintained in a plastic condition, stretching the plastic product during its passage through the bath and subsequently removing the product from the bath, washing the product to remove solvent therefrom and drying and collecting the product.

11. Process 'for the manuiacture of artificial filaments, threads, ribbons and like products, which comprises extruding a solution of cellulose acetate in a neutral solvent medium through a suitable shaping device into an aqueous coagulating bath containing diacetone alcohol in a concentration of about 60% wherein it is brought to and-maintained in a plastic condition, stretching the plastic product during its passage through the bath and subsequently removing the product from the bath, washing the product to remove solvent therefrom and drying and collecting the product. 7

12. Process for the. manufacture ofartificial filaments, threads, ribbons and like products,

which comprises extruding a solution of cellulose acetate in a neutral solvent. medium through a suitable shaping deviceinto an aqueous coagulating bath containing ethyl lactate in a concentration of about 45% wherein it is brought to and maintained in a plastic condition, stretching the plastic product during its passage through the bath and subsequently removing the product from the bath, washing the product tov remove solvent therefrom and drying and collecting the product.

13. Process for the manufacture of artificial filaments, threads, ribbons and like products, which comprises extruding a solution of cellulose acetate in a neutral solvent medium through a suitable shaping device into an aqueous c'oagu lating bath containing diethyl tartrate in a concentration ofbetween 25 and 65% wherein it is brought to and maintained in a plastic condition, stretching the plastic product during its passage through the bath and subsequently removing the product from the bath, washing the product to remove solvent therefrom and drying and col.- lecting the product. v

WILLIAM ALEXANDER 131cm. PERCY FREDERICK COMBE SOWTER. 

